fix(actions): always emit message create for own messages (#10211)

* fix(actions): always emit message create for own messages

* fix: don't re-cache

* fix: user can be missing

---------

Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

packages/discord.js/src/client/actions/MessageCreate.js

@@ -16,8 +16,8 @@ class MessageCreateAction extends Action {
       }
 
       const existing = channel.messages.cache.get(data.id);
-      if (existing) return { message: existing };
-      const message = channel.messages._add(data);
+      if (existing && existing.author?.id !== this.client.user.id) return { message: existing };
+      const message = existing ?? channel.messages._add(data);
       channel.lastMessageId = data.id;
 
       /**